NEW YORK -LRB- CNN -RRB- -- A rash of bank robberies in New York has the city 's police commissioner worried that criminals have turned banks into `` virtual cash machines '' and some wondering whether tough economic times are fueling the trend .

A surveillance camera captures a bank robbery suspect in New York on December 2 .

On Monday alone , robbers targeted five banks in the Big Apple , some striking in broad daylight and near famous landmarks .

Police called the incidents unrelated , but they 're just the latest examples of the growing tally of hold-ups .

Bank robberies in New York have risen 54 percent compared with last year , with criminals committing more than 430 in the past 12 months , according to the New York police department .

`` As it stands now , they 've turned -LSB- banks -RSB- into virtual cash machines , '' New York Police Commissioner Raymond Kelly said .

Bank robberies are also up in many areas across the country , including San Diego , California , and Houston , Texas , federal law enforcement experts told CNN .

It 's enough for some to link the trend to the rash of layoffs , the plummeting stock market and the bust in the real estate values , all of which have left many Americans in dire financial straits .

`` It makes me think that the recession is making people go to extreme measures , '' a woman who frequents one of the banks robbed Monday told The New York Times . Watch where the robbers struck ''

But Kelly said it 's not clear whether the bad economic times are fueling the unusual spike .

`` People want to say ... it 's because of the economy . I think it 's too early to make that statement , '' he said .

CNN security analyst Mike Brooks agreed , adding that although there are typically many bank robberies during the holidays , there are no data to suggest that any recent spike was caused by the economy .

Another expert said it 's possible that the difficulty of finding a job right now may be a factor , but he doubted that law-abiding citizens are turning to crime to make ends meet .

`` It 's hard to attribute the bank robberies to people who were let go from Lehman Brothers or other organizations that are in trouble , '' said Alfred Blumstein , who has researched criminal justice for 20 years and is a professor of operations research at Carnegie Mellon University 's Heinz College .

`` I would anticipate that people who rob banks have been involved with crime before because that 's not where one is likely to start , '' Blumstein said .

A person who might turn to robbing banks is someone in their late teens or early 20s who has already broken the law and has decided to move on to a bigger target , he added .

`` Bank robbery is a very high-risk activity , because most banks have various surveillance equipment in place , and it requires a degree of aggressiveness that otherwise law-abiding folks are not likely to take on , '' Blumstein said .

Some officials say the modern , customer-friendly design of banks -- with easy access to tellers and cash -- is too tempting for robbers .

`` We do n't like the business plan that makes a bank look like a living room , '' Kelly said `` We -LSB- advise -RSB- just some common sense provisions , such as so-called bandit barriers , so that tellers have some option to act when somebody puts a note in front of them . ''

In fact , bank robbers have simply handed tellers a note in a vast majority of hold-ups in New York . Kelly put the figure at 80 percent and added that although the rest of the robbers claimed to have a gun , many did n't actually show it .

Mike Smith , president and CEO of the New York Bankers Association , is meeting with the NYPD to see what more can be done to discourage robbers . He said banks have a significant amount of security , some of which may not be visible to the public .

`` Are there enhancements ? Obviously . Criminals talk to each other , they know what 's going on , but typically they are apprehended , '' Mike Smith said .

CNN 's A. Pawlowski contributed to this report .

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Bank robberies in New York have risen 54 percent compared with last year

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On Monday alone , robbers targeted five banks , some striking in broad daylight

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NYPD : Not clear whether the bad economic times are fueling the spike

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Expert doubts law-abiding citizens are turning to crime to make ends meet